1. Field of the Invention
The present invention relates to a drum type printer, and more particularly, to a drum type printer having a mechanism for adjusting a transverse position of a printed image.
2. Description of the Prior Art
In Japanese Patent Publication No. 2542489 issued Oct. 9, 1996, there is described a device for adjusting a transverse position of a printed image for a stencil printer having a drum unit rotatably supporting a cylindrical printing drum and slidably mounted in a body of the printer along the longitudinal axis of the printing drum, so as to be manually dismountable out of the printer body at the end of the sliding drawout movement, wherein the printed image transverse position adjustment device comprises guide means provided in the printer body for guiding the drum unit in the sliding direction, a movement transmission system for moving the drum unit in the sliding direction along the guide means for a minute distance, a motor for driving the movement transmission system, and clutch means for optionally connecting or disconnecting the movement transmission system to or from the drum unit.
In the printed image transverse position adjustment device for a stencil printer described in the above-mentioned patent publication, the drum unit is slid as a whole for an adjustment of a transverse position of a printed image along the guide means for dismountably mounting the drum unit in the printer body.
The drum unit of this type, when it is the drum unit of a stencil printer, incorporates therein an ink container to serve as a source of a printing ink and an ink pump for transporting the ink from the ink container to the inside of the printing drum, so that the weight of the drum unit as a whole is substantial such as about 10 kg or more. Further, such a drum unit has a length such as about 40 cm or more and a diameter such as about 20 cm. Therefore, for the drum unit of such weight and size to be inserted into a drum unit bore of the printer body or drawn out of the drum unit bore by the hands of a man or woman, what is required for the guide means for guiding the drum unit relative to the printer body for the insertion and the drawout thereof into and out of the printer body is a strength rather than a fineness.
On the other hand, an adjustment of a transverse position of a printed image provided on a print sheet is of the order of 10 mm at the largest, and often requires a fineness smaller than 1 mm, so as to be more desirable as the fineness is higher.
In view of the above points, it will not be rational to conduct such an adjustment of a transverse position of a printed image that is in a range of 10 mm at the largest and is more desirable when it is more fine, by such macro-structural guide means for guiding the drum unit, a heavy article, over a guide distance extending so long as about 40 cm for the insertion and the drawout thereof into and out of the printer body.